Yes, we have a fairly robust model of orbital and cislunar meteoroid data. As you can imagine, it's full of math and tables and fancy words that convey almost nothing to a nontechnical audience. So let me demystify it in general terms.
Space is big. Really big. You might think it's a long way down the road to the chemist/pharmacist, but that's just peanuts to space. Even in the worst circumstances, the flux band we worry about is still just a few dozen particles per square meter per year.
As you can imagine, there are many dimensions (sometimes literally) to the problem. Particle size? Particle velocity? Particle flux? Particle mass density? Particle composition? Time of year? Proximity to the lunar surface?
Most micrometeoroids are comet debris. They're flimsy and light. The bigger the particle size, the far lower the flux. Flux peaks in late summer, when Earth and Moon go through the Perseids.
Space suits (even of the Apollo era) do an excellent job of absorbing the stuff our models predict. The thing that will ruin your day is secondary flux if you're in the ejecta cloud of a major strike on the Moon, something that may have happened maybe once since the space program began. You get 100x the nominal flux, depending on how close you stand.
